HORSE HEAVEN HILLS — Even in the driest grain-growing region of the world, farmers have to wait for their amber waves to dry.

Kyle Degraffenreid is up and stationed at his combine by 6:45 a.m., but the wheat stalks that blanket the Horse Heaven Hills plateau south of Prosser still are too damp to harvest from the morning dew.

While they wait, the 17-year-old and his fellow workers at the Berg Partnership wheat farm wash windows, clean filters and grease the parts of two John Deere combines with tires taller than they are.

“I have OCD about my combine,” Degraffenreid said. “I like being in luxury while I’m driving.”

As dryland wheat growers in a vast stretch of Benton and Klickitat counties wrap up the 2013 harvest, they’re thinking about lower-than-average yields, fluctuating prices, routine equipment mishaps and, yes, clean windows. They spend little time worrying about the controversy over genetically modified wheat.

The GMO scare — genetically modified organisms — began in April when a grower in Eastern Oregon noticed his wheat showing resistance to the herbicide Roundup. An investigation by the U.S. Department of Agriculture determined it was a genetically modified strain manufactured by Monsanto.

Critics of genetically altered crops worry about unforeseen effects on the environment, such as resistance to conventional herbicides.

Three months after the discovery, officials still have not said where it came from, leaving winter wheat growers unsure how to plan for the 2014 crop, which they will seed this fall.

Most of the fields in the area surrounding the Oregon grower are soft white wheat, the same variety as about 80 percent of Washington’s.

“I can tell you there’s plenty of frustration,” said Dana Herron, a member of the Washington Grain Commission and a Connell seed marketer. However, nobody has canceled their seed orders with him.

After the discovery, buyers in Korea and Japan briefly stopped imports to conduct extra testing, but both countries — which have an aversion to any genetically altered food — have resumed purchases.

However, gauging the controversy’s effect on prices, which fluctuate based on a variety of factors, would be impossible, Herron said.

“To draw a correlation would be speculation,” he said.

In fact, local and global weather has caused plenty of uncertainty on its own.

Herron’s own wheat farm lost 40 percent of its crop due to frost in the late fall and a heat wave in early May.

Horse Heaven Hills growers, who produce almost exclusively hard red winter wheat, felt the same sting.

The Berg Partnership expects average yields of between 18 and 20 bushels per acre, down from the Benton County average of 30, said Nicole Berg, a partner in the business and a member of fourth generation to run the farm.

Rain in June helped but couldn’t bring yields back to normal.

“Without the spring rains we’ve had, I’m not sure we would have even been cutting wheat,” said Berg, a member of the Washington Association of Wheat Growers. “At one point I didn’t even think I was going to harvest.”

Meanwhile, worldwide stocks of wheat are healthy, which has tempered demand and therefore price, said Scott Yates, a spokesman for the Washington Grain Growers based in Spokane.

Hard red winter prices were roughly $8 per bushel Thursday at the Portland docks, according to the federal Department of Agriculture. That’s down from the $9.50 average last year.

However, China, the world’s largest wheat consumer, has increased imports due to weather problems in its own grain-growing regions.

Prices and international trade aside, the Berg family in the Horse Heaven Hills last week scrambled to finish harvest on their 3,600 acres in time to return two leased combines. They started around the Fourth of July.

“We’ll run pretty late tonight,” said Matt Berg, Nicole’s brother, of Kennewick on Thursday as he and employee Jesus Muñoz tended to a loose belt on one of the sickle blades.

After a few more minutes of prep work, Degraffenreid and Woody Simmons, 23, both family friends from the Puget Sound area, fired up their machines and crept through the wheat at about 6 mph.

They were guided by GPS, cooled by air conditioning and entertained by stereo systems equipped with iPod adapters.

“It’s like a walk in the park,” Degraffenreid said.

Days were long, however ­— sometimes 12 to 14 hours each.

“I guess it’s kind of a good thing because I’ll be ready for school and getting up early,” he said.

• Ross Courtney can be reached at 509-930-8798 or